RE:RE:Fine Diamonds & Variances Explained...Part 2How many tonnes before you get a 1 carat diamond? The question for De Beers is how does the frequency and value of diamonds greater than 0.5 carats behave in the 5034 and Hearne pipes. Mountain Province has provided a detailed breakdown of the size frequency, but the numbers on their own do not make much sense. It is perhaps more intuitive to ask how many tonnes does it take before you recover a 1 carat diamond, or how big does your parcel of diamonds have to be before you can expect a 1 carat stone in it? For the East Lobe the results so far indicate that a stone bigger than 1 carat shows up every 19 tonnes, or in every 27 carat parcel recovered with a 1.5 mm sieve. A stone weighing 0.5-1.0 carats shows up every 6 tonnes of East Lobe rock, or in a parcel of at least 9 carats. The 1999 bulk sample, which was a blend of all three lobes that yielded 1,005 carats from 573 tonnes, included 113 stones weighing 0.5-1.0 carats and 42 stones greater than 1 carat. In other words, a 1 carat stone showed up every 14 tonnes or in every 24 carat parcel, while a stone weighing 0.5-1.0 carats showed up in every five tonnes, or in every 9 carat parcel. In the latest results the recoveries are broken down for the West and Center lobes. The West Lobe yielded 843 carats from 437 tonnes which included 49 stones greater than 1 carat and 111 weighing 0.5-1.0 carat. For the West Lobe that translates into a 1 carat stone every 9 tonnes or every 17 carat parcel, and a 0.5-1.0 carat stone every 4 tonnes or 8 carat parcel. The Center Lobe yielded 372 carats from 399 tonnes which included 21 stones greater than 1 carat and 50 stones weighing 0.5-1.0 carats. For the Center Lobe that translates into a 1 carat stone every 19 tonnes or, and this is very interesting, one in every 18 carat parcel. A 0.5-1.0 ct/t stone in the Center Lobe shows up every 8 tonnes, or in every 7 carat parcel. One immediate observation which Mountain Province also emphasizes in its news release is that the West Lobe, although of similar grade to the East Lobe, has a coarser size distribution than the East Lobe. When we look at only stones greater than 3 carats, the difference becomes more obvious: a stone bigger than 3 carats shows up every 318 tonnes in the East Lobe, but it takes only 62 tonnes from the West Lobe to produce a stone bigger than 3 carats. The comparison is valid because the sample base of 437 tonnes for the West Lobe is smaller than the East Lobe (635 tonnes). We cannot judge the Center Lobe, which yielded only one stone bigger than 3 carats (4.6 ct), because its lower grade furnished a diamond parcel half the size those furnished by the West and East Lobe samples. But it is very interesting to note that in terms of how many carats must be recovered before you get a 1 carat stone, the West and Center Lobe kimberlite are very similar.